Read I Became the Daughter-In-Law of the Villain Because I’m Terminally Ill! Manga:
I’ve reincarnated as the young daughter-in-law of a villain who was taken in for his deceptive plans. The problem is that I’m terminally ill, so I’m going to die when I become an adult. "Luckily, I know how to cure it, but..." If I don’t die at the right time, my father-in-law—no, the villain, Duke Ecarde—might more.. kill me just to achieve his goals! But what kind of kid could actually adjust to this kind of household? "I want to live happily with Father and Evan for a long time... cough! Cough!" Me. I’m "that kid."